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Dynamics of infection and pathology induced by the aporocotylid, Cardicola laruei, in spotted seatrout, Cynoscion nebulosus (Sciaenidae)


McElroy, EJ and Nowak, B and Hill-Spanik, KM and Granath, WO and Connors, VA and Driver, J and Tucker, CJ and Kyle, DE and de Buron, I, Dynamics of infection and pathology induced by the aporocotylid, Cardicola laruei, in spotted seatrout, Cynoscion nebulosus (Sciaenidae), International Journal for Parasitology, 50, (10-11) pp. 809-823. ISSN 0020-7519 (2020) [Refereed Article]

Copyright Statement

Copyright 2020 Australian Society for Parasitology.

DOI: doi:10.1016/j.ijpara.2020.03.016


The sciaenid Spotted Seatrout (Cynoscion nebulosus) are infected by blood flukes (Cardicola spp.). A 2 year survey in estuaries of South Carolina, USA, showed that adult flukes and granulomas occurred throughout the year but their prevalence was highest in summer (61% and 84%, respectively), indicating an unusually high level of infection for wild fish. Granulomas remained after adult flukes could no longer be found. PCR-Restriction Fragment Length Polymorphism (RFLP) of a subsample of specimens allowed identification of Cardicola laruei as the only species infecting these seatrout during the period of study. Mean intensity of infection by flukes was higher in female seatrout, suggesting endocrine and/or immune system involvement. The prevalence of granulomas declined sharply in winter, indicating possible mortality of infected seatrout as this species is known to be cold-sensitive. Granulomas were studied using histology, immunohistochemistry, and transmission electron microscopy. Eggs were encapsulated by an inner core of dark epithelioid cells, and an outer core of large epithelioid cells undergoing epithelialization. Fibrosis was observed around granulomas and some granulomas detached from the surrounding damaged myocardium. Numerous inflammatory cells appeared mobilised around granulomas and pathology could be severe, in some cases showing grossly visible blister-like extrusions scattered in the damaged epicardium. At the gross level, some granulomas possessing eggs with live miracidia were observed at the surface of the epicardium. These findings suggest that granulomas carrying both dead and live eggs can clear the fish heart by host-mediated transport through the myocardium, as is known to occur in related human Schistosoma infections.

Item Details

Item Type:Refereed Article
Keywords:blood fluke, granuloma, epidemiology, ultrastructure, immunochistochemistry, epithelialization
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Fish pests and diseases
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - aquaculture
Objective Field:Aquaculture fin fish (excl. tuna)
UTAS Author:Nowak, B (Professor Barbara Nowak)
ID Code:140948
Year Published:2020
Web of Science® Times Cited:3
Deposited By:Fisheries and Aquaculture
Deposited On:2020-09-16
Last Modified:2021-02-11

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